import java.util.HashMap;
import java.util.Map;

public class Ma {
    public static void main(String[] args) {
        Map user = new HashMap();
        user.put("name", "Tom");
        user.put("age", 18);
        user.put("gender", 'M');
        System.out.println("姓名：" + user.get("name") + "，性别：" + user.get("gender") + "，年龄：" + user.get("age"));
        user.remove("gender");
        System.out.println("最终键值对个数：" + user.size());
    }
}